5G mms is the high speed service. But its affected by wind, buildings and cars. And the phones that have it are expensive because the circuitry uses heaps of power and the battery is the most expensive part of the phone.
So mms is mainly being promoted for stationary devices, and in buildings that have repeater emitters.
The 5G low band phones are cheaper to make than 4G because the circuitry is more efficient so you can use smaller batteries.
5G has a more efficient algorithm for ordering incoming/outgoing signals, so like-for-like there is higher speed and less freezing. But in new areas the telcos just build fewer towers so the speed is no better than 4G.
When you upload a song, you indicate whether it has copyright and who owns it, Then, whenever its played they pay the copyright owner based on an audience size basis, similar to Spotify.
If you don't, the copyright owner informs Google, and they close that link.
Even if you have music playing in the background of an instructional video, the copyright holders will go after you.